Person of Interest (2011–2016)
3 user 1 critic

Zero Day 

They wait ten days for a new number due to a system virus, suspecting Root is the problem. It's for Ernest Thornhill, who isn't who, or what, he is supposed to be. At stake is The Machine - will it remain with Finch or end up with Decima?


Jeffrey G. Hunt (as Jeffrey Hunt)


Jonathan Nolan (created by), Amanda Segel | 3 more credits »

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Episode cast overview, first billed only:
Jim Caviezel ... John Reese
Taraji P. Henson ... Joss Carter
Kevin Chapman ... Lionel Fusco (credit only)
Michael Emerson ... Harold Finch
Amy Acker ... Root
Brett Cullen ... Nathan Ingram
Jay O. Sanders ... Special Counsel
Carrie Preston ... Grace Hendricks
John Nolan ... John Greer
Al Sapienza ... Detective Raymond Terney
Kevyn Morrow ... IAB Detective Ed Solis
Opal Alladin ... Claudia Sugarman
Sarah Shahi ... Sameen Shaw
Carter Gill ... Office Drone
Mike Masters ... ESU Captain


It's been ten days since the machine has provided a number, which means Carter has had ten days of dead bodies piling up. Finch discovers that a company called Decima is responsible for the virus which is causing these problems of inconsistency. The machine finally does dispense a number, it belonging to Ernest Thornhill, whose business of late has been buying up pay phone companies. As Finch and Reese track Thornhill, who they have yet actually to see, they find out some important information about him and exactly why the machine dispensed his number. But also aware of that fact is Root, who, using her own brand of persuasion, convinces Finch that they need to work together to battle Decima and the virus. Reese becomes aware that Root is back in the picture, he who gets some help from an old acquaintance in tracking Finch and Root. Their competing goals will all come to a head at midnight Eastern time, when the virus is scheduled to do its job. Meanwhile, Carter, in conjunction with ... Written by Huggo

Plot Summary | Plot Synopsis


TV-14 | See all certifications »






Release Date:

2 May 2013 (USA) See more »

Company Credits

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Technical Specs


Sound Mix:




Aspect Ratio:

16:9 HD
See full technical specs »

Did You Know?


Harold tells Root that the machine restarts itself "1.618 seconds later". 1.618 is the first four digits of the mathematical Golden Ratio. See more »


Once again, a cellular call between Reese and Carter ends with a dial tone when he hangs up. No dial tone is heard at the end of a call on a cell phone. See more »


Root: If we go to your one true phone, we'll tip our hand and they'll kill us before it even rings.
Harold Finch: Then I suppose we'll need a plan.
Root: Have a little faith in your creation. We don't need a plan if Ernest Thornhill has one.
See more »


References Person of Interest: Dead Reckoning (2013) See more »

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User Reviews

Mind Blowing

One of the best episodes this season. Full of twists and turns

Jim Caviezel, you are a beauty. The whole episode keeps us on the edge and it kept me wondering what's gonna happen next. As the seasons unfold a lot of things about the MACHINE are disclosed.

Though I'd really want to see the past footage when Nathan dies and from where did Finch got his limping leg and injured spine.

This was helluva episode, as good as the season finale. Just imagining if the penultimate episode left us on a cliffhanger, what's going to be the finale.

Eagerly looking forward to it. Cheers Jonathan Nolan, one great Television series you have made. It just got renewed for 3rd season too (Excited for that)

Hope this one makes up to 8-9 or 10 seasons...just can't seem to get bored of it. kudos guys, thanks for PERSON OF INTEREST.

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